Eggs and dairy products are one of the most common sources of the foodborne illness, but infections with salmonella — which cause an illness known as salmonellosis — also come from eating poultry, meat, fruits, vegetables, spices, and nuts, among other things. In April, an outbreak linked to the herbal supplement kratom sickened at least 132 people in 38 states.

Some people also get sick by interacting with animals, especially reptiles, amphibians, and birds.

Children, especially those under 5, are at the highest risk, and illnesses caused by these infections are most severe for infants, older people, and anyone with a weakened immune system.

A person can get sick from eating food that has been contaminated by one of 2,300 types of salmonella bacteria. The two most common types found in the US, Salmonella enteritidis and Salmonella typhimurium, account for about half of human infections, according to the US Department of Agriculture.

The bacteria live in the intestinal tract of animals. When animal feces contaminate meat, poultry, or dairy products, the bacteria spread. Cross-contamination can occur when produce or other foods come into contact with the bacteria.

Most people who get sick develop diarrhea, a fever, and abdominal cramps within three days, and the illness can last for about four to seven days. Many recover without treatment, aside from rest and rehydration, though it can take several months for bowel movements to normalize.

In particularly severe cases, diarrhea can get bad enough that warrants hospitalization. If the infection spreads from the intestines into the bloodstream, it can be fatal without antibiotic treatment. A small number of cases can also cause joint pain from reactive arthritis that can last for months or years.

The most effective ways to prevent infection with salmonella are keeping surfaces and hands clean and cooking foods properly. Thomson Reuters

How to prevent infection

Since salmonella infections can be severe, food-safety experts recommend a variety of steps to prevent them.

Animal products should be kept separate in grocery carts and refrigerators and should be cooked to safe temperatures to kill pathogenic bacteria — according to the USDA, steaks, chops, and roasts should reach a minimum internal temperature of 145 degrees Fahrenheit, and ground meat should reach 160 degrees. For poultry, it's 165, and for egg dishes, it's 160.

Leftovers should be refrigerated within two hours, or one hour in very hot conditions.